In the diagnosis and treatment of breast cancer, it is often necessary to remove multiple tissue samples from a suspicious mass. The suspicious mass is typically discovered during a preliminary examination involving visual examination, palpitation, X-ray, MRI, ultrasound imaging or other detection means. When this preliminary examination reveals a suspicious mass, the mass must be evaluated by taking a biopsy in order to determine whether the mass is malignant or benign. Early diagnosis of breast cancer, as well as other forms of cancer, can prevent the spread of cancerous cells to other parts of the body and ultimately prevent fatal results.
A biopsy can be performed by either an open procedure or a percutaneous method. The open surgical biopsy procedure first requires localization of the lesion by insertion of a wire loop, while using visualization technique, such as X-ray or ultrasound. Next, the patient is taken to a surgical room where a large incision is made in the breast, and the tissue surrounding the wire loop is removed. This procedure causes significant trauma to the breast tissue, often leaving disfiguring results and requiring considerable recovery time for the patient. This is often a deterrent to patients receiving the medical care they require. The open technique, as compared to the percutaneous method, presents increased risk of infection and bleeding at the sample site. Due to these disadvantages, percutaneous methods are often preferred.
Percutaneous biopsies have been performed using either Fine Needle Aspiration or core biopsy in conjunction with real-time visualization techniques, such as ultrasound or mammography (X-ray). Fine Needle Aspiration involves the removal of a small number of cells using an aspiration needle. A smear of the cells is then analyzed using cytology techniques. Although Fine Needle Aspiration is less intrusive, only a small amount of cells are available for analysis. In addition, this method does not provide for a pathological assessment of the tissue, which can provide a more complete assessment of the stage of the cancer, if found. In contrast, in core biopsy a larger fragment of tissue can be removed without destroying the structure of the tissue. Consequently, core biopsy samples can be analyzed using a more comprehensive histology technique, which indicates the stage of the cancer. In the case of small lesions, the entire mass may be removed using the core biopsy method. For these reasons core biopsy is preferred, and there has been a trend towards the core biopsy method, so that a more detailed picture can be constructed by pathology of the disease's progress and type.
The first core biopsy devices were of the spring advanced, “Tru-Cut” style consisting of a hollow tube with a sharpened edge that was inserted into the breast to obtain a plug of tissue. This device presented several disadvantages. First, the device would sometimes fail to remove a sample, therefore, requiring additional insertions. This was generally due to tissue failing to prolapse into the sampling notch. Secondly, the device had to be inserted and withdrawn to obtain each sample, therefore, requiring several insertions in order to acquire sufficient tissue for pathology.
The biopsy apparatus disclosed in U.S. Pat. No. 5,526,822 to Burbank, et al was designed in an attempt to solve many of these disadvantages. The Burbank apparatus is a biopsy device that requires only a single insertion into the biopsy site to remove multiple tissue samples. The device incorporates a tube within a tube design that includes an outer piercing needle having a sharpened distal end for piercing the tissue. The outer needle has a lateral opening forming a tissue receiving port. The device has an inner cannula slidingly disposed within the outer cannula, and which serves to cut tissue that has prolapsed into the tissue receiving port. Additionally, a vacuum is used to draw the tissue into the tissue receiving port.
Although the Burbank device presented an advancement in the field of biopsy devices, several disadvantages remain and further improvements are needed. For example, the inner cutter must be advanced manually, meaning the surgeon manually moves the cutter back and forth by lateral movement of a knob mounted on the outside of the instrument or by one of the three pedals at the footswitch. Also, the vacuum source that draws the tissue into the receiving port is typically supplied via a vacuum chamber attached to the outer cannula. The vacuum chamber defines at least one, usually multiple, communicating holes between the chamber and the outer cannula. These small holes often become clogged with blood and bodily fluids. The fluids occlude the holes and prevent the aspiration from drawing the tissue into the receiving port. This ultimately prevents a core from being obtained, a condition called a “dry tap.” In light of the foregoing disadvantages, a need remains for a method of tissue removal that reliably applies a vacuum.